Acidity, properly
- Pleasant acidity is brightness and comes with sweetness. Short-brew sourness comes alone.
- Citric is citrus, malic is apple, phosphoric is cola-ish, acetic is vinegar, lactic is yogurt.
- Acid names describe a kind of brightness. You taste the blend, and roasting shifts it.
- Chlorogenic acids bring bitterness and a drying edge more than tang.
Bright is not sour
In a good cup, acidity reads as brightness: juicy, lively, the thing that makes a Kenyan taste wide awake. Bright acidity arrives with a sweet edge; take that away and the same tang turns sharp and thin.
Sour arrives alone
The cupping protocol calls it brightness when it’s pleasant, and “sour” when it isn’t. The sourness of a cup brewed too short is sharp, thin, often a little salty, and arrives empty-handed.
The acids, introduced
Match each acid to the food it tastes like.
- Citric — lemon
- Malic — green apple
- Phosphoric — cola
- Acetic — vinegar
- Lactic — yogurt
Citric is lemon, malic is green apple, phosphoric is cola, acetic is vinegar, lactic is yogurt. Five words for five kinds of brightness.
Where each one shows up
Citric is lemon and orange, malic is green apple, phosphoric is cola, acetic is vinegar, lactic is yogurt. Tap through them for what each one does in a cup.
A vocabulary, not a lab report
When Danish researchers spiked coffee with single acids at their real levels, experts couldn’t name them, and only citric sat clearly above what tasters can detect. What you taste is the blend: a choir, not soloists.
Roast turns it down
Which roast usually gives the brightest cup?
Answer: Light. Citric and malic fade as beans darken, so the brightest cups come from the lightest roasts.
When acetic gets loud
Acetic acid is a pleasant sharpness in a whisper. Louder, it is something else.
A cup smells plainly of vinegar. What does a cupper write down?
Answer: A defect. Acetic acid forms in fermentation and roasting, and a vinegar smell usually means the processing ran too far.
The acid that isn’t bright
The biggest acid family in a green bean never makes the fruit list. Chlorogenic acids add a little tang, plus a bitter bite and a drying edge, and roasting breaks much of them down into more bitter compounds.
Three signals, one sip
- tart
- A taste. In a good cup it reads as brightness; in a short brew it reads as sour.
- bitter
- A taste too. Much of it is what roasting makes of the chlorogenic acids.
- drying
- Not a taste at all — a feel. The next lesson pulls it apart from bitterness.
“Brightness with a little sweetness is welcome, I find; sourness that arrives alone may be shown the door.”